Hey everyone. Great Weber tuning thread! Until now, I only had the "Weber running too rich thread" I am glad to see so much good info on here.

I am so new to Carbs... I have some very basic questions.

1-I have a Weber 34. It is about two months old. I read recently about tuning with a vacuum gauge. Will this only work with ported vacuum? I only have manifold vacuum (constant vacuum even at idle).

2-Do you count the turns on the AF screw from where the spring bottoms out? I am not sure if the screw is completely seated when the spring is fully compressed or not.

3-My jeep stumbles and sometimes pops at the carb when the second barrel opens up if my rpms are below 2K.. Is this just a common "Carb" thing? Or a symptom I don't have this tuned right?

4-Finally... Do you guys have any info on the Weber 34?.. I know it may not be a "real" Weber.. But it still should be tunable.

THANKS!

First thing first here....
Shawn, this is the best and most radical change in pictures. 10+

MattyMcF90
The Solex 34-DGEC does have an "S"park port for ported vacuum advance to the distributor, this is where you would hook up a vacuum gauge and get to zero "ported" vacuum at idle. The 34-DGEC has some inconsistencies that I have found with the couple of carbs I have worked on. The enrichening holes seem to be drilled at different heights from the absolute closed throttle plate position. Some 34-DGEC can open the throttle plate more, before exposing the enrichening holes than on others. The advantages "could" be that you can get a little higher idle and therefore use a smaller idle jet. The disadvantages are a stumble on the low speed circuit therefore needing to bring in the main circuit earlier to cover that up.
What I would suggest in your situation is slow the engine down with the carburetor as slow as you can get it... Then, reset the initial ignition timing to 10-12 BTDC. This should increase the idle speed. Then slow the engine down with the carburetor as slow as you can get it... Then, reset or recheck the initial ignition timing to 10-12 BTDC. Repeat this procedure until the engine is as slow as it can be and there are no changes in the initial ignition timing. Then idea of this is to close the throttle plates below the drilled enrichening hole in the throat of the carburetor. At this point you will have already found the "Leanest, Best idle" with the mixture screw. It is the position of this mixture screw that will tell you if you need to use a larger or a smaller jet. We let the engine tell us what it wants, and typically when the low speed circuit has stumbles fumbles and variable smoothness you need a little more fuel.
Let me know how many turns your idle speed screw is in from not touching the throttle lever to where your engine idles. On the 32/36 DGEV this can not be in more than 1 1/2 turns with zero ported vacuum at the "S" port. The idle speed screw setting on the 34-DCEC can vary from carburetor to carburetor due to the enrichening holes not being drilled consistently. I hate to "Flame" the Solex just because of it being owned by Magnetti Marrelli = Weber.

At this point you will have already found the "Leanest, Best idle" with the mixture screw.

Uptillnow-

Thanks for the reply. After rereading this post, I just also realized I have a vacuum leak in my adapter plates that I will have to fix first. Hopefully a quick sanding will do the trick (fingers crossed)

I was confused by the lean-best idle statement. After doing your idle-speed screw adjustment you mentioned, should I then find the Lean-best idle as Shawn explained on page 2?

OK - so re-timing to 12 BTDC allowed me to get the screw down to 1.5 turns out (I had it set to 8 per the Nutter forum but 12 seems much better). This put me at about 6-700 rpms. I may have been able to go a little lower but the engine would hardly idle at anything less.

I had to back out my AF screw to smooth out and raise the idle a little.. Now it is 6 turns out.. Is this "too far" the engine fumbles/stumbles/slows when it is anything less than 4 turns out.

OK - so re-timing to 12 BTDC allowed me to get the screw down to 1.5 turns out (I had it set to 8 per the Nutter forum but 12 seems much better). This put me at about 6-700 rpms. I may have been able to go a little lower but the engine would hardly idle at anything less.

I had to back out my AF screw to smooth out and raise the idle a little.. Now it is 6 turns out.. Is this "too far" the engine fumbles/stumbles/slows when it is anything less than 4 turns out.

Were do we go from here?

MattyMcF90
The "TRICK" here is to be sure that “Step 1” is complete, and then we will move on.
First, it is imperative to be on the idle circuit…. The leading edge of the throttle plate can not expose the enrichening holes in the throat of the carburetor. Typically there is ZERO vacuum at the advance port “PORTED” or “S” vacuum source and the idle speed screw CAN NOT be turned in more than 1 ½ turns exposing the enrichening holes. Second, we “bracket” the mixture screw to find that sweet spot. When we find that, we turn the mixture screw in until a slight hesitation, back the mixture screw out slightly until smooth then back in until just ever so slightly stumble. This is the “Lean” best idle. Then, you will re-set your initial timing to (as you are saying 12 BTDC) Repeat this process a couple of times until there is no need to readjust anything. I have seen the Jeeps idle speed around 600-700RPM with a Weber, it may be slightly higher or lower with the Solex 34-DGEC. Also, with a Weber you would expect to change the idle jet up a ½ size or down a ½ size depending on where you find the “Lean Best Idle”. Weber = more than 2 ½ mixture screw turns out we would increase the idle jet ½ size, below 1 ½ turns out we would decrease the idle jet by ½ size. All of this jet adjustment absolutely depends on completing Steps 1 & 2, speed screw and zero vacuum, then the Lean Best Idle found, then initial timing.
UPTILLNOW

UPTILLNOW-
I am pretty sure I am now not exposing any of the 3 enriching holes. When I took off the carb in an attempt to fix the leak at the mounting plates, I took a series of pictures at different idle speed screw settings. At my setting of 1.5 turns, I do not have them exposed. If it goes to 2, the first enriching hole is about 20% exposed.

Still, I am having a hard time eliminating the vacuum.. I have to have the idle speed screw barely touching (less than 1/2 turn) for the vacuum to significantly drop.

I will play with it more this week and see if I can come up with anything else.. If i can figure out how to post pictures.. i'll add those as well.
Just for the record.. I currently have idle jets at 55/47.5 and main jets 175/174
matt

UPTILLNOW-
I am pretty sure I am now not exposing any of the 3 enriching holes.

Still, I am having a hard time eliminating the vacuum.. I have to have the idle speed screw barely touching (less than 1/2 turn) for the vacuum to significantly drop.

I will play with it more this week and see if I can come up with anything else.. If i can figure out how to post pictures.. i'll add those as well.
Just for the record.. I currently have idle jets at 55/47.5 and main jets 175/174
matt

Good to hear back from you.
These Weber 32/36 DGEV on 6 cyl engines NEED a .75mm primary idle jet. If not, (55/47.5) you will won't have enough fuel for your engine to run on at idle, therefore having some vacuum reading at idle.
This also sounds like the nut on the throttle shaft holding the throttle lever on is too tight, (more than finger tight and one or two flat spots tighter).
If this is the case... the throttle shaft will be in a slight bind, therefore not allowing the throttle plate to come to a complete close. So, when you back out the idle speed screw, then turn it in you will only "increase" opening the plate slightly because it is already open some. This is why the ZERO vacuum at idle is the better way to diagnose these types of problems. This is where it gets tricky and why some people just give up and say F...It.
Take a Deep Breath and take another look at this. I also recall you have a 34-DGEC Solex, there could be some differences in jet sizes here.
Where did you get your SOLEX? Is it new, or was it already on your vehicle?
Let me know.
UPTILLNOW

Thanks for the quick reply and all the help so far... I tired to not bind the linkage when installing the carb, but I will take another look at it to make sure it isn't holding the plate open. Good idea.

I purchased this carb directly from redlineweber.com. It is a bit of a long story.. but this Jeep came with a Weber 34 that I could never get to work right, so I replaced it with another Weber 34 (should have just gotten the 32/36...). You can buy these carbs when searching JCwhitney or Quaratech. Check out the link here http://www.quadratec.com/products/51312_57_07.htm

Contrary to what others have said, Redline Weber will provide warranty and technical support for the Weber(Solex) 34. Jose usually answers the phone and he is very helpful. I will have to talk with him about getting some larger jets to try out. (The jets Mcmud linked-to do not look anything like the idle jets on the Weber 34?)

Thanks for the quick reply and all the help so far... I tired to not bind the linkage when installing the carb, but I will take another look at it to make sure it isn't holding the plate open. Good idea.

I purchased this carb directly from redlineweber.com. It is a bit of a long story.. but this Jeep came with a Weber 34 that I could never get to work right, so I replaced it with another Weber 34 (should have just gotten the 32/36...). You can buy these carbs when searching JCwhitney or Quaratech. Check out the link here http://www.quadratec.com/products/51312_57_07.htm

Contrary to what others have said, Redline Weber will provide warranty and technical support for the Weber(Solex) 34. Jose usually answers the phone and he is very helpful. I will have to talk with him about getting some larger jets to try out. (The jets Mcmud linked-to do not look anything like the idle jets on the Weber 34?)

Hey MattyMcF90
I am glad to see you are getting support for your Solex 34-DGEC from Jose. I believe he will help you jet this thing properly, the way it should have come in the box.
Just a quick note to eliminate any confusion here.
redlineweber.com doesn't sell the reboxed Solex made into a Weber by using stickers, boxes, logos and propaganda.
Redline only sells the Weber that is made in Spain. JCWhitney does sell the REDLINE products and Quadratec sells the reboxed stuff. Jose does not work at REDLINE he is at Weber Direct, this means they sell directly to the public rather than being the importer and/or distributing like REDLINE imports and distributes through their distributors. Magnetti Marelli has allot to do with Weber parts in this country. Weber is also the largest or second largest manufacture of fuel injection parts that Magnetti Marelli is very involved with distribution through out the World or Earth. I am not sure who actually owns the Weber name and logo, but I am sure who ever they are they do not own the plant, specifications or manufacturing, distributions of what we old people affectionately call “Original Weber.” Once again I am glad to see that Jose is going to get you a little larger jet to make this work great. Good Luck
UPTILLNOW

Thanks for the background info. It's too bad a Weber just can't be a "Weber" anymore with everything being moved overseas...

One last technical question.. I heard at one time an engine can be damaged by running to lean. Is this true? How do I know if I am too lean and causing damage? Pull the plugs and read them or is there an easier way?

Thanks for the background info. It's too bad a Weber just can't be a "Weber" anymore with everything being moved overseas...

One last technical question.. I heard at one time an engine can be damaged by running to lean. Is this true? How do I know if I am too lean and causing damage? Pull the plugs and read them or is there an easier way?

Yep, Yep, Yep... I don't get it either, why someone would own the name and logo and "think" it is OK to decieve the public with their reboxed product and ruin a perfectly good reputation of the acutual Weber procuct. Check out this web page, I hate to "Flame" the Solex, just the people claim it a Weber with their bait and switch sales approach. $$$$$$$$$Genuine Weber: Will the real genuine Weber please stand up

I don't think I would worry about any engine damage from your engine being too lean in this case.
This lager jet is just a slight fuel adjustment for your drivability issues.
When you run a turbo and force larger volumes of air into the same space without any fuel adjustments you would probably see some blistering to melt-down depending on how lean, how much power, how long you ran it etc.
UPTILLNOW